Basic Trigonometric Identities sin2θ + cos2θ = 1 ; −1 ≤ sin θ ≤ 1 ; −1 ≤ cos θ ≤ 1 ∀ θ ∈ R sec2θ − tan2θ = 1 ; |sec θ| ≥ 1 ∀ θ ∈ R cosec2θ − cot2θ = 1 ; |cosec θ| ≥ 1 ∀ θ ∈ R Important Trigonometric Ratios | Trigonometry sin n π = 0 ; cos n π = (-1)n ; tan n π = 0 where n ∈ I sin 15° or ; Trigonometric Functions of Allied Angles | … [Read more...]